That got me to wondering what the person behind the original Windows Defender thought of all this, so yesterday I did a little digging and got him on the phone. He is one Adam Lyttle, 22, a software developer in Adelaide, South Australia. See this morning’s story for all the details about the situation.

The quick summary: A law firm for Microsoft contacted Lyttle last month, informing him that the product was infringing on the Windows trademark. On that basis, and keeping in mind that his Windows Defender had been discontinued anyway, Lyttle agreed to give up rights to the name. He was surprised and disappointed to find out later that Microsoft actually planned to use it. He’s not happy that the company wasn’t straightforward about its intentions, although he says he wouldn’t have asked for payment even if he had known it planned to use the name.

Microsoft says it discovered Lyttle’s product in the course of investigating the possibility of using the Windows Defender name. It was a pretty clear case of infringement, which Lyttle acknowledges, and companies are obligated to pursue such cases, when they find them, to protect their marks.

Another lawyer I spoke with yesterday says the law firm and Microsoft went about things the right way — that it was not only legal and ethical but also a logical business decision for them to not volunteer the fact that Microsoft might use the name. (However, they would have needed to be truthful if he had asked about it.) A lot of people would have tried to negotiate a payment if they had known the company was headed in that direction.

Lyttle had actually stopped development of his Windows Defender program nearly a year ago. As part of the agreement with Microsoft, he said, the company is contacting the various shareware sites on his behalf to have it taken down. To check out some of his other software, see this page on his site. He offers an RSS aggregator, called Simple News Reader, among other programs.

As for the WindowsDefender.com domain, that was owned by Richard Harrison, 38, whose day job is working as a principal technologist at a company called Content Master, which does contract work for Microsoft. Harrison’s free Windows Defender service provides scripts and tips for defending against spyware, viruses and other malware. I just got off the phone with Harrison, who said Microsoft contacted him in a very nice way last week to talk about assuming the domain, agreeing to cover his costs. Harrison is shifting his service to the site www.pcdid.com, standing for PC Defense in Depth.